The type or namespace IAppBuilder could not be found(missing using a directive pr an assembly reference)

Question

I am working on an Asp.Net MVC 4 Application in which I am using SignalR 2.0.1 and I Mapped it using Owin Startup class and it worked fine at first.

All of a sudden

Answer 1

My Visual Studio 2013 for some reason didn't realize that the references paths existed. The yellow exclamation mark in front of the references was shown for all the added packages. I checked ../packages/ but all files existed, i also opened the .csproj file which referenced the correct paths.

Closing and opening the solution returned quite a lot of errors, and could not load the projects included in the solution.

Restarting Visual Studio 2013 saved the day for some unexplained reason.